1. Field of the Invention
The present invention relates to the control of subsea structures and the control of blowout preventers. More particularly, the present invention the relates to systems for controlling the operation of the controls of the blowout preventer. Additionally, the present invention relates to electrically-powered wrenches as used for the actuation of the controls of the blowout preventer.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
When drilling in deepwater from a floating drilling vessel, a blowout preventer stack is typically connected to a wellhead at the sea floor. A diverter system is also mounted under the rig sub-structure at the surface via a marine riser system. The blowout preventer stack is employed to provide a means to control the well during drilling operations and provide a means to both secure and disconnect from the well in the event of the vessel losing position due to automatic station keeping failure, weather, sea state, or mooring failure.
A conventionally configured blowout preventer stack is typically arranged in two sections, including an upper section (i.e. the lower marine riser package) which provides an interface to a marine riser via a riser adapter located at the top of the package. The riser adapter is secured to a flex-joint which provides angular movement to compensate for vessel offset. The flex-joint assembly, in turn, interfaces with a single or dual element hydraulically-operated annular-type blowout preventer, which allows for the stripping of drill pipe or tubulars which are run in and out of the well. Also located in the lower marine riser package is a hydraulically-actuated connector which interfaces with a mandrel, typically located on the top of the blowout preventer stack's lower section. The blowout preventer stack's lower section typically includes a series of hydraulically-operated ram-type blowout preventers connected together via bolted flanges in a vertical plane creating a ram stack section. In turn, the ram stack section interfaces to a hydraulically-latched wellhead connector via a bolted flange. The wellhead connector interfaces to the wellhead, which is a mandrel profile integral to the wellhead housing, which is the conduit to the wellbore.
Conduit lines integral to the marine riser provide for hydraulic fluid supply to the blowout preventer stack control system and communication with the wellbore annulus via stack-mounted gate valves. The stack-mounted gate valves are arranged in the ram stack column at various positions so as to allow circulation through the blowout preventer stack column depending on which individual ram is closed.
The unitized blowout preventer stack is controlled by means of a control system containing pilot and directional control valves which are typically arranged in a control module or pod. Pressure regulators are typically included in the control pod to allow for operating pressure increase/decrease for the hydraulic circuits which control the functions on the unitized blowout preventer stack. These valves, when commanded from the surface, either hydraulically or electro-hydraulically direct pressurized hydraulic fluid to the function selected. Hydraulic fluid is supplied to the blowout preventer stack via a specific hydraulic conduit line. In turn, the fluid is stored at pressure in stack-mounted accumulators, which supply the function of the directional control valves contained in redundant control pods mounted on the lower marine riser package or upper section of the blowout preventer stack.
A hydraulic power unit and accumulator banks are installed within the vessel to provide a continuous source of replenishment fluid that is delivered to the subsea blowout preventer stack-mounted accumulators via a hydraulic rigid conduit line and stored at pressure. Recent deepwater developments have placed increased demands for well control systems so as to require dramatic increases in the functional capability of the subsea blowout preventer stack and, in turn, the control system operating methodologies and complexities. These additional operational requirements and complexities have had a serious effect on system reliability, particularly in the control system components and interface.
In the past, various patents and publications have described techniques of the control of the blowout preventer systems. Additionally, various prior art patents and publications have been directed to controlling the functions of other subsea structures, such as subsea trees. In each of these subsea structures, there are several valves that are incorporated into the structure that must be controlled so as to carry out the desired function.
An early publication directed to the diverless control of such subsea structures is found from an article in Oil & Gas Journal of Apr. 5, 1993. This article describes a diverless subsea system in which an integrated template system is connected by short jumpers to the various valves of the subsea structure. As a result, the integrated template system can be lowered so as to be in proximity to the blowout preventer. An ROV can then be lowered into the water and operatively controlled from the surface so as to move in position so as to operate controls on the integrated template. The operation of these controls effectively allows for the control of the functions of the blowout preventer, along with the operation of other subsea structures.
U.S. Pat. No. 7,216,714, issued on May 15, 2007 to G. E. Reynolds, describes a modular, distributed, ROV retrievable subsea control system for use with a module adapted for use in a modular blowout preventer stack for use subsea. The control module includes a housing that is adapted to be manipulated by a remotely operated vehicle (ROV) with a stab portion adapted to be received into a blowout preventer stack control module receiver. Control electronics are adapted to control a predetermined function with respect to the BOP stack. These control electronics are disposed within the housing and connected to one or more controllable devices by a wet mateable connector interface.
U.S. Pat. No. 7,222,674, issued on May 29, 2007 also to G. E. Reynolds, describes a distributed function control module adapted for use in a blowout preventer stack for use subsea. This control module also comprises a housing that is adapted to be manipulated by a ROV. A stab portion is adapted to be received into a blowout preventer stack control module receiver. Control electronics are disposed within the housing and are connected to one or more controllable devices by a wet mateable connector interface. The control electronics are adapted to control a predetermined function of the BOP stack.
U.S. Pat. No. 7,690,433 issued on Apr. 6, 2010 also to G. E. Reynolds, provides a distributed function control module adapted for use in a modular blowout preventer stack for use subsea. This control module includes a housing that is adapted to be manipulated by a remotely operated vehicle. A stab portion is adapted to be received into a blowout preventer stack control module receiver. Control electronics are disposed within the housing and are connected to one or more controllable devices by a wet mateable connector interface. The control electronics are adapted to control a predetermined function of the blowout preventer stack.
U.S. Patent Publication No. 2010/0181075, published on Jul. 22, 2010 also to G. E. Reynolds, teaches a distributed function control module having a housing that is adapted to be manipulated by a ROV. A stab portion is adapted to be received into a BOP stack control module receiver. Control electronics are disposed within the housing. The control electronics are connected to one or more controllable devices by a wet mateable connector interface. The control electronics are adapted to control a predetermined function with respect to BOP stack.
Unfortunately, with these prior art patents, it is necessary to employ an ROV in order to carry out the actuation of the various functions of the blowout preventer. ROVs are very expensive. Skilled personnel are required so as to properly manipulate the ROV so that the ROV can engage with the wet mateable interfaces. In the event of a need to control a function of the blowout preventer, the ROV must be deployed from a ship and then moved into a proper position in the deep water. This is a very time consuming operation. As such, the ROV may not be available in order to carry out the control of the blowout preventer in emergency circumstances. As such, a need has developed whereby the control of the blowout preventer can carried out remotely by a vessel located on the surface of the body of water.
It is known in the past that ROV can carry torque wrenches thereon. A torque wrench is a tool that is used to precisely apply a specific torque to a fastener, such as a nut or bolt. It is usually in the form of a socket wrench with special internal mechanisms. Typically, torque wrenches are used where the tightness of screws and bolts is crucial. It allows the operator to measure the torque applied to fastener so that it can be matched to the specification for a particular application. This permits proper tension and loading of all parts. A torque wrench measures torque as a proxy for bolt tension. In the subsea environment, such torque wrench can be carried by the ROV to a desired location. If it is desired to operate the torque wrench in the subsea environment, then the ROV can supply hydraulic power to the hydraulically-powered torque wrench. As a result, the ROV is available so as to apply the torque wrench to the controls of a blowout preventer, as needed. For example, if a particular control of the blowout preventer must be actuated, then the ROV can deliver the torque wrench to its desired location at the control of the blowout preventer. The torque wrench is hydraulically-actuated so as to manipulate the control. In all circumstances, it is still necessary for the ROV to be deployed, to travel to the location of the blowout preventer, to align the torque wrench with the controls of the blowout preventer, and then to apply the necessary forces to the controls.
It is an object of the present invention to provide a control system for a blowout preventer that is diverless and ROV-less.
It is another object of the present invention to provide a subsea control system whereby acoustic signals from an acoustic signal generator can be utilized so as to control the functions of the blowout preventer.
It is another object of the present invention to provide a subsea control system which minimizes the expenses and complexities associated with the control of the blowout preventer and other subsea structures.
It is still another object of the present invention to provide a subsea control system whereby any function on the blowout preventer can be controlled by the acoustic control unit and the acoustic signal generator.
It is still another object of the present invention to provide a subsea control system whereby electrically-powered torque wrenches can be effectively utilized for the actuation of the controls of the blowout preventer.
It is a further object of the present invention to provide a subsea control system whereby batteries associated with such electrically-powered torque wrench can be easily recharged.
It is still a further object of the present invention to provide a subsea control system that is easy to use, relatively inexpensive and easy to manufacture.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.